Method of forming twist-drills.



A. WARD.

METHOD OI FORMING TWIST DBILLS.

APPLICATION FILED 21:12.14, 1908.

950,645. Patented Mar. 1, 1910.

VWTA/Essz's fiwmon flflmyabv J7 Wwul, a .7 fizz/W ATTORNEY UNITED STATESPATENT OFFICE.

ALVIN WARD, OF JACKSON, OHIO, ASSIGNOR TO THE CLEVELAND TWIST DRILLCOMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

METHOD OF FORMING TWIST-DRILLS.

To all whom it may concern:

Be it known that I, ALVIN WARD, a citizen of the United States, residentof J ackson, county of Jackson, and State of Ohio, have invented a newand useful Improvement in Methods of Forming Twist-Drills, of which thefollowing is a specification, the principle of the invention beinghereinafter explained and the best mode in which I have contemplatedapplying that principle, so as to distinguish it from other inventions.

My invention relates to methods of forming the helical flutes and landsof twist drills or the like, the object of such invention being to formsuch flutes and lands in a blank rod with a minimum waste of materialand without leaving the product with deleterious internal molecularstrains.

The said invention consists of a method hereinafter fully described andparticularly set forth in the claims.

The annexed drawin and the following description 4 set forth in detail acertain method and means for carrying out the invention, such disclosedmethod and means, however, constituting but one of various forms inwhich the principle of the invention may be applied.

In said annexed drawing: Figure 1 is a plan of one of the diesconstructed in accordance with that part of my invention relating to themeans for carrying out my improved method. Fig. 2 is an end elevation ofsuch die, and Fig. 3 is a cross-sectional view taken upon the planeindicated by line III-III 0 Fig. 1. Fig. 4 is an elevation of a blankrod and Fig. 5 is a similar View of the finished product of my improvedmethod and means for carrying out same.

The die block A is formed with a semicylindrical depression a which isangularly traversed by a projection a, itself of semicylindricalcross-section. This projection is made of a height substantially equalto about one-half the extreme depth of the depression a as shown in Fig.2 and its base intersects the cylindrical surface of the depression. Thecross-sectional area of the depression a is made such that when theblank rod is laid therein and upon the projection a only a small amountof lateral play Specification of Letters Patent.

Application filed February 14, 1908.

Patented Mar. 1, 1910. Serial No. 415,981.

as permitted for a purpose hereinafter speci- A similar depression a isformed upon another part of the block whose extreme portions are madeaccurately of a semicylindrical form whose cross-sectional area is madeexactly equal to one-half of the circular cross-sectional area of therequired finished forging. An angularly placed portion a of thedepression a is made of greaterv depth than the end portions of thedepression a as shown in Fig. 3, so as to present a greatercross-sectional area on a plane having an angularity substantially equalto the angle of the required flute and indicated b the line ww, Fig. 1.Protruding upwar ly from this enlarged portionof the depression is aprojection a which is also angularly placed with reference to thedepressions axis as shown and is furthermore of a semi-cylindricalcross-section, the middle part of such cross-section correspondingsubstantially to the cross-section of the desired finished forging. Thisprojection a is furthermore of greater height than that of projection a.

In carrying out my improved process, the

die block A is placed in a suitable foundation to form an anvil and asimilar die block provided with depressions and projections exactlysimilar to those just described but reversed to assume the positionindicated in dotted lines in Fig. 1, is secured to the head of asuitable drop, trip or steam hammer.

The blank to be operated upon is heated to a suitable temperature andthen placed in the depression a and upon the project-101i a so as tobrin the latter in a position WlllCll 'will be occupied b that end ofthe flutes adjacent to the shan of the drill. In this position (seedotted lines F i 1), as was previously stated, only a sma 1 amount oflat-- eral movement of the blank is permitted so that the projection awill be ro erly centered with relation to the blanl i. he hammer is nowoperated to bring the other portion of the die down upon the to of theblank, whereby the projection a an the corresponding projection of theother portion of the die are caused to make two oppositely disposeddepressions of opposite angularlty,

pression' previously as will be readily understood. The blank is thengiven a helical movement in the direction of its 'axis and the hammeringoperation continued, the projection a being used as a guide. Twooppositely disposed flutes are thus formed which have not, however,their final depth or form. The blank so imressed is now transferred tothe groove 0? of the die block and placed therein so as to cause theprojection a to enga e the flutes formed in the abovedescrib operation.The upper movable die is now caused to descend upon the blank in anumber of successive blows so as to further enlarge the imformed. Suchaction produces a projectlon having the contour of the depressed portiona of the depression a and the projection a, the metal expanding into theportion a After the required number of blows have been delivered toproduce this contour, the blank is turned so as to impart thereto ahelical movement in the direction of'the blanks axis, the projection abeing used as a guide for such purpose. This brings a succeeding portionof the blank into the field of operation of the die and the requirednumber of blows are now s ruck to produce a result upon this portion ofthe blank such as above described. In this manner every portion of theblank may be presented to the action of the die and two continuoushelical and oppositely disposed flutes thereby formed upon the blank toproduce the finished product.

The expanded portions of the blank after being formed are brou ht intothe field of action of the cylindrica end portions of the depression aand thereby caused to assume the exact required size. The completedforging is now placed in a straightening die to give it a rectilinearform.

All surfaces of the depression a are rounded slightly as shown andparticularly those surfaces which form the connection between thecylindrical portion thereof and stasis the depressed portion a thereofso that the product of the above described operation will on completionpresent a smooth and uniform appearance.

The action of the cylindrical end portions of the depression is such asto compress the enlarged portion formed in the vicinity of theprojection a which results in the slight contraction of the outerportion of the flutes. This contract-ion permits the edges of the flutesto present a sharp line when the drill is ground to its final exteriorform.

1 therefore particularly point out and distinctly claim as my invention:

l. The method of forging the flutes in twist drills which consists infirst forming upon the blank and solely by means of two complementarydies, two oppositely disposed helical flutes of less depth than that ofa desired forged flute; then subjecting the flute so formed to a furtheroperation by means of additional dies whereby a further depth of theflutes is imparted, such latter depth being that of the desired finishedforged form.

2. In a method of forging twist drills or the like, the steps whichconsist in simultaneously subjecting opposite sides of ablank to theimpression of two tool elements of opposite angularit with reference tothe blanks axis, whi e imparting to such blank a helical motion in thedirection of its axis, one of said tool elements being used as a guidefor such motion, simultaneously with such impressing action permittingthe blank to expand laterally and only immediately adjacent to such toolelements, while the latter are acting, and then reducing the di ameterof such expanded portion of the blank.

ALVIN WARD.

